基于GIS的长江中下游地区洪灾风险分区及评价

国内外近几年的发展表明,在所有可能避免和减轻自然灾害的措施中,最简单有效的方法就是通过在科学研究基础上进行风险区划,将自然灾害管理提高到风险管理的水平.在长江流域数字化地图的基础上,选取不同重复期(20,50,100年),及包括1870年历史洪水和1931,1935,1954,1991,1995,1996,1998,1999和2002年共10次洪水,借助Arcview地理信息系统的空间分析和叠加功能,对长江中下游地区的洪水灾害危险性进行了初步评价.首先参考洪水灾害淹没图和相关历史文献记录资料,构建10次洪水受灾县(市)分布图;其次对这10次洪水受灾县(市)分布图进行叠加,得到长江中下游地区洪涝灾害风险性评价图.分析表明:长江中下游地区洪水风险的分布是有规律的,而且具有明显的地理意义.有4个明显的高危风险区,分别是洞庭湖、鄱阳湖两湖平原的湖滨地区和公安以下的长江中游河段的沿江一带,尤其是荆江河段以及两江相夹地势低洼的江汉平原;沿高危风险区外侧为高风险地区,重点在汉江下游、资、沅、澧水、清江流域、皖沿江地区以及太湖流域的部分地区;沿长江于高危风险和高风险地区两侧分别为风险较小地区;其他地区对于洪水灾害而言则为安全地区.评价结果与长江中下游的实际情况基本吻合.

GIS based risk zoning and assessment of flood disaster in the middle and lower reaches of the Yangtze River Basin

Based on the digital topographical map and the data about 10 heavy floods since 1870 in the Yangtze River basin,a primary zoning and assessment of flood risk in the middle and lower reaches of the Yangtze River has been studied using Arcview GIS platform with strong function on space analysis and overlap.Firstly the flood-affected area mapping for the 10 heavy floods was conducted based on historical record data;secondly the flood risk assessment map for the Yangtze River basin is made by overlapping the 10 flood affected area distribution.The result shows that the distribution of heavy flood-inundated area has some law in the middle and lower reaches of the Yangtze River with obvious geographical characters.There are 4 extreme flood risks area,i.e.Dongting Lake basin,Poyang Lake basin and the downstream of the Gong'an county along the Yangtze River,especially in Jingjiang River and the Hanjiang Plain with low-lying land between the Yangtze River and the Hanjiang River.(Around) the extreme risks area there are high flood risk area,mainly in the lower reaches of Hanjiang River and along the Zhijiang River basin,Yuanjiang River basin,Lishui River basin,Qingjiang River basin and Taihu Lake basin.Around the extreme flood risks area and the high flood risk area along the Yangtze River is the areas with middle and lower flood risk,and the other is the safety area.The result is identical with the actual situation of the area.